gamma correcting MR Car Paint Shader

# 1 11-07-2013 , 02:48 PM

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Anyone know how to set up a gamma correction node for the mental ray car paint shader?

Do all the contributing colors need correction?

Can you use the same gamma correction node for all ??

I am assuming you don't have to gamma correct the shader node for the edge color bias?

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# 2 11-07-2013 , 08:07 PM

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If you're not piping any files into it's attributes, you don't need to gamma correct anything, as shaders already follow a linear workflow.

Imagination is more important than knowledge.

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# 3 11-07-2013 , 08:28 PM

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Thanks for the info, I was told when adding colors to the shaders they should be gamma corrected.

Didn't make any sense to me but what the heck better to find out n ow than later.

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# 4 11-07-2013 , 09:48 PM

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I've found myself gamma correcting everything except the reflection color. The default shader is using colors at full saturation(which is kind of weird) so on first glance it seemed ok. I can't say that I've tested it as much as the mia mat though.

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# 5 12-07-2013 , 12:41 AM

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I did notice the full saturation.

So I guess it wouldn't hurt to gamma correct the colors?

I did norice that the edge color bias is getting it's input from a different shader, I guess I need to gamma correct this as well or does this not appear in the viewport?

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# 6 12-07-2013 , 03:11 AM

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I've found myself gamma correcting everything except the reflection color. The default shader is using colors at full saturation(which is kind of weird) so on first glance it seemed ok. I can't say that I've tested it as much as the mia mat though.

Originally Posted by Gen

That's incorrect. If you're using the standard color swatches in the mia materials, they don't need to be, or should be, gamma corrected, because the color input is already linear.

Imagination is more important than knowledge.

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# 7 12-07-2013 , 10:56 AM

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Eh? I'm under the impression that Maya color swatches that we choose from the color picker are not linear.

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# 8 12-07-2013 , 12:37 PM

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Hmmm... That's interesting... I took a look around, and it seems that you're right Gen. It's odd however, as 3ds max's colors are linear with the mia material, so I assumed it would be the same with Maya; but I guess not. :/

Imagination is more important than knowledge.

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# 9 12-07-2013 , 08:38 PM

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Man, you scared me lol, that would've been such a bummer since I thought I'd finally wrapped my head around this stuff. I do remember reading that Max handles it differently, I suppose this is part of the reason why many users complain about the state of Maya rendering.

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# 10 13-07-2013 , 05:42 PM

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yeah nothing in Maya is Linear until you 'fix it'

Even then after a shot is complete we have a LUT that will then guage what color grade issues we may have and so on.....

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# 11 13-07-2013 , 06:16 PM

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Sorry guys it is not Maya but rather the decision of Autodesk management to put more support in to Max and not Softimage or Maya.

Autodesk buys their development more than it does internally as well. I am surprised they have not purchased a newer rendering engine by now.

Max still sucks when it comes to rigging and nurbs modeling.

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# 12 21-09-2013 , 02:35 AM

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Car Paint shader is based on the Renderman shader by Peter Stuart Also from the research paper A Simple Layered RGB BRDF Model by Xavier Granier and Wolfgang Heidrich. The model simulates the interaction (interference) of light with itself due to a thin substrate. To completely capture this effect, the simulation would have to be performed over the whole spectrum of light. This is obviously too much work for a shader to do, so this model avoids sampling the whole spectrum by simulating only the RGB colors and then interpolating between the results using a phong-like approach.

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# 13 22-09-2013 , 11:11 AM

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Thanks Emerson, for the background info.

However I have already fixed the gamma issue.

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# 14 21-03-2014 , 12:42 AM

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Auto painting has changed as time pass by. Nowadays, car painting offer different types to choose from. There is acrylic painting that refers to lacquers, enamels etc and it's a water-based. Cost involves in painting your car so turned to an online search on "fast payday loans online" for your auto paint.

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# 15 21-03-2014 , 12:50 AM

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Auto painting has changed as time pass by. Nowadays, car painting offer different types to choose from. There is acrylic painting that refers to lacquers, enamels etc and it's a water-based. Cost involves in painting your car so turned to an online search on "fast payday loans online" for your auto paint.

Originally Posted by AkikoHendricks

Hmmm... Yes, YES!!! That's the answer! Wait, what?...

Sampson

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gamma correcting MR Car Paint Shader

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